We limited methadone prescriptions in this study to those prescribed to treat pain by excluding prescriptions in which dosing instructions indicated the methadone was prescribed for maintenance, oral or effervescent methadone formulations unless the dosing schedule indicated more than once a day dosing, or the dosing schedule was once a day unless the instructions indicated the methadone was prescribed for pain. Buprenorphine is not currently indicated for pain treatment in the VHA and was not included in this analysis. Opioid analgesic dose was calculated as morphine equivalents